Another popular topic was the proposed Gigafactory that is to produce huge volumes of lithium-ion cells starting in 2018.

After announcing the four states it was evaluating as locations, Tesla has been relatively silent of late on the gigafactory--and Musk predictably got questions from analysts on any progress.

Musk announced on the earnings call that Tesla has a letter of intent signed with Panasonic. "With us, that's actually not that big of a deal," he said, since Panasonic had always been the designated partner.

And, he said, it hopes to break ground on the first location "probably next month"--and the second location probably a month or two after that.

And, he added, California is back in the running, no matter how "improbable" that may have seemed--due to strong efforts by Governor Jerry Brown and his staff. The issue had been time to completion, with California having a complex and lengthy approval process for building on green-field sites.

The gigafactory must be up and running by the time the company's third-generation electric car goes into production in 2018, or Tesla will be building cars for which it has no battery packs.

Mining companies responsive

Tesla CTO JB Straubel said the two companies had created a joint working team in touch almost daily to answer mutual issues. He said they were working constantly to make sure both companies were staying "on the same page,"

They are "quite comfortable," Straubel said, that the two companies are heading toward a final agreement "sometime later this year" to partner on the Gigafactory.

"We are talking to various different people in parallel," Straubel said, noting that Panasonic "doesn't do" many different parts of the process of making not only cells but also the precursor materials--meaning those potential partners would be "complementary" rather than competitive with Panasonic.

And, Musk added, "we are cautiously optimistic" that the factory will produce the 30-percent cost reduction in lithium-ion cell costs it has targeted.

There is a lot of opportunity for innovation in the precursor materials, he said; Tesla has had interesting discussions with some of the big mining companies, including large nickel mines in Canada.

"We are really positively surprised" by the potential for cost reductions in raw materials from those suppliers, Musk said--adding that the mining companies had said, "No one ever calls us" to ask about price cuts in what is otherwise a commodity material.